1. Field of Invention
This invention pertains to a self-cleaning litter box. More particularly, this invention pertains to a control system for a pet litter box with a mechanical self-cleaning mechanism.
2. Description of the Related Art
Domestic cats kept as pets are usually trained to use a litter box for elimination of both liquid and solid wastes. A cat litter box is normally made of a liquid impermeable material so that a cat's urine will not leak through the box. The box may optionally have a cover. The litter used in these boxes may be one of any number of particulate litter or other materials that absorb moisture from the waste of the cat. The litter material may also suppress odor from cat waste. Some forms of litter form clumps when wet. Usually, a cat will bury its solid waste in the litter material in the box. The litter box requires periodic cleaning to remove the cat's solid waste and the litter that is saturated with urine.
Thus, a number of devices have been proposed for automating cleaning of cat litter boxes. The following patents illustrate the use of motorized cleaning mechanisms. U.S. Pat. No. 5,048,465, titled “Self-cleaning kitty litter box,” issued to Carlisi on Sep. 17, 1991, discloses a kitty litter box with a motor, timing device, and a rake. U.S. Pat. No. 5,226,388, titled “Automated cat litter disposal system,” issued to McDaniel on Jul. 13, 1993, discloses an automated cat litter disposal system for a cat litter box. U.S. Pat. No. 6,082,302, titled “Self-cleaning litter box,” issued to Thaler, et al., on Jul. 4, 2000, discloses a self-cleaning litter box for cats with a comb drive. The litter box is rectangular and the comb moves through the litter until it encounters an obstruction, at which time it stops. The comb has a sensor for sensing contact with any obstruction encountered by the comb as it moves through the box.
U.S. Pat. No. RE36,847, titled “Automated self-cleaning litter box for cats,” issued to Waters on Sep. 5, 2000, discloses an automated self-cleaning litter box for cats. The Waters patent describes a system for moving a comb through the litter contained in a rectangular litter box. The system is responsive to entry and exit of the cat from the litter box. In addition, Waters provides an improved disposal receptacle and alarms to report an insufficient litter supply and a fill disposal receptacle.